Record gas prices: 20 straight days
Price for gas tops $4 a gallon in 11 states and Washington, D.C., according to AAA survey.
NEW YORK (CNNMoney.com) -- Retail gas prices hit record highs for the 20th day in a row, motorist group AAA's Web site showed Tuesday.
The nationwide average for a gallon of regular unleaded rose to $3.937, up slightly from $3.936 the previous day.
The climb in gas prices, which have steadily risen over the past three weeks, comes amid the start of the summer driving season, which unofficially kicked off over the Memorial Day weekend.
The AAA survey shows gas prices are up about 9% from a month ago and nearly 23% higher from year-ago levels. The average price for gas has passed the $4 a gallon mark in 11 states, as well as in Washington, D.C.
The most expensive state for buying gas is Alaska, where a gallon of regular unleaded costs an average of $4.201. The second most expensive state is Connecticut, where a gallon of gas costs $4.196, according to AAA.
The least expensive state for purchasing gas is Wyoming, where a gallon costs $3.751 a gallon on average. The second least expensive state for gas is Missouri, where a gallon runs $3.753 a gallon.
In the face of surging prices, consumers are cutting back on the number of miles they clock on the road. Americans drove 11 billion miles less in March this year than the same month a year ago, the Department of Transportation said Monday.
The Federal Highway Administration's "Traffic Volume Trends" report, produced monthly since 1942, showed that estimated vehicle miles traveled on all U.S. public roads in March fell 4.3% - the sharpest drop for any month in the report's history.
Gas prices have increased by a quarter over the past year, while the price of crude oil has more than doubled.
The July futures contract for crude is trading around $132 a barrel on Tuesday morning, after hitting a record high price above $135 a barrel last week. Crude prices have been pushed to hit record highs on supply concerns, a weak dollar and increasing global demand for diesel fuel. 
